Telephone system



Jan. 2l, 1930. C. E. LoMAxv TELEPHON: SYSTEM 2 Sheets-Sheet 1 k vFiled April 9, 192e )wal Jan. 21, 1930. c. E. LoMAx 1,744,396

' TELEPHONE SYSTEM l Filed April 9, 1926 2 Sheets-Sheet 2 I mnu @Humm o D. D

v- Imm- Elaren :a ELnmax Patented Jan. 21, 1930 UNTED STATES PATENT OFFICE CLARENCE E. LOMAX, OF OAK PARK, LLINOS, ASSTGNOR, BY MESNE ASSIGNMENTS, TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE TELEPHONE SYSTEM Application led April 9,

This invention relates to telephone systems in general, but is more particularly concerned with telephone systems having both automatic exchanges and manual exchanges with interconnecting trunk lines, and in which service is given to pay stations.

In a system of this kind, it is often desirable to operate all the pay stations in the system manually. Ordinarily in such a case the line from each pay station must extend to a manual exchange, where it may terminate in a jack at an operators position, even though the pay station is in the close vicinity of an automatic exchange.

By this invention a method is proposed in which the line of a pay station, which is to be operated manually and is in the close vicinity of an automatic exchange, may terminate at that automatic exchange from where a connection may be automatically extended over one of the regular interoiiice trunks to a manual exchange. In response to the initiation of a call at the pay station, an operator at the manual exchange will be signalled and will then complete the connection in the ordinary manner.

A particular object of this invention then may be stated to be the production of a new ringing repeater to terminate or be accessible to a pay station line at an automatic exchange, which has access through the medium of associated switching mechanism to the regular interoifice trunks extendingl to a manual exchange.

A feature of the new ringing repeater is contained in the means which is responsive to the initiation of a call for automatically signailing the operator at the manual exchange.

Another feature of the invention is the provision of means for giving the calling party at the pay station the busy signal'when all the trunks extending to the manual exchange accessible to the switching mechanism associated with the ringing repeater are busy, this signal being given continuously until one of the trunks becomes idle, whereupon the connection will automatically be extended over this idle trunk to the manual exchange.

The object of the invention and its features, those mentioned and others not specifically 1926. Serial No. 100,828.

stated will be fully explained with reference to the accompanying drawings, comprising Figs. l, 2 and 3. The first two drawings, when Fig. 2 is placed to the right of Fig. 1, show by way of example by means of the usual schematic circuit diagrams sufficient of a telephone system such as referred to above to which this invention pertains for a complete and thorough understanding of the features and operation of the invention. Fig 3 shows the trunki'ng layout of the autonatic exchange.

In Fig. 1 is shown the pay station A, which is equipped with' the usual coin collect box B. The line comprising conductors 2 and 8, from the pay station A terminates at the automatic exchange in the individual ringing repeater RR and is accessible at contacts 2, 3 and l in the banks of the regular connectors.

Other pay station lines may also terminate at the automatic exchange in ringing repeat-- ers having associated switching mechanisms similar to ringing repeater RR and may also be accessible in the banks of regular connectors.

Permanently associated with the ringing repeater RR is the rotary switching mechanism RLS. Mechanically, the switching mechanism RLS is similar to the well known rotary type of line switch having no normal position and always moving in a forward direction. The ringing repeater and the operation of the switching mechanism RLS in conjunction therewith forms a particular part of this invention and will be described in detail in later paragraphs.

The trunk comprising conductors 104 and 106 extends from the automatic exchange to the manual exchange. At the automatic exchange, the trunk terminates in the rotary line switch C, and is accessible at contacts 104', 105', and 106 in the banks of rotary connectors.

The rotary line switch C is also of the well known rotary type having no normal position and always moving in a forward direction, and operates to hunt a. trunk to an idle first selector for extending a call from the manual to the automatic exchange. `As many similar trunks with associated line switches may be provided as are necessary to carry the traflic between the two exchanges. The trunk, comprising conductors 104 and 106, together with the other similar interoi'lice trunks, is also accessible in the banks of the rotary switching mechanisms, such as RLS.

Associated with each interoflice trunk is a chain relay. lhen all the trunks are busy, the chain relays perform circuit changes that affect the operation of the ringing repeaters and associated switching mechanisms as will be described in later paragraphs.

In Fig. 2, equipment at the manual exchange is shown. Each trunk from the automatic exchange terminates at the manual eirchange in a jack such as jack J, which is the regular answering jack. Each trunk is also provided with a jack such as jack J for connecting the dial l) thereto.

The operators posit-ion is equipped with a plurality of cords such as cord OC. The cord OC, like the other cords, is an ordinary coinmon battery cord having the answering and calling plugs P and P', respectively, and the ringing and the listening key K for associating either in ringing generator G or the op erators head set HS with the cord.

In Fig. 3 is shown the layout of equipment in the automatic exchange. Pay station A, ringing repeater RR, switching mechanism RLS, and rotary line switch C are the switches shown in detail in Fig. 1 under the same designations. Trunk T corresponds to the trunk comprising conductors 104 and 10G of F ig. 1. A represents the substation of a regular automatic exchange subscriber. C is a. rotary line switch terminating the line from substation A and together with rotary line switch C in which trunk T terminates, has access to first selectors. The iirst selectors have access to the various connector' groups in the automat-ic exchange. Only one connector of the rotary connector group is shown. The rotary connectors of this group have access through their banks to substations such as A', pay stations such as A, and also to trunk T and other similar trunks.

With this description of the system and the apparatus used in mind, a further understanding and appreciation of the invention may be gained from a detailed description of the operations performed in extending a call from a pay station to the operator at the manual exchange. For this purpose, it may be assumed that a party at the pay station A desires to extend a call and removes his receiver.

Responsive to the removal of the receiver at the substation A, a circuit is closed for the line relay of the ringing repeater RR which extends from the loop across the line conductors 2 and 3 at the substation A, armatures 13 and 14 and their resting contacts, through the upper and lower windings of relay G to battery and ground, respectively. Relay 0 operates and closes a circuit for the release relay 9 at armature 15. Relay 9 ope 'ates and at armature 19 place ground potential on the private normal conductor 1 connected to the private test Contact 4 to mark the line to the substation A busy and prevent its being connected with by one of the regular connector at this time. At armature 21 a point in the busy tone circuit is closed, and at armature 20 a circuit is closed for the slow acting line relay 11 which ma".7 be traced from ground on the common conductor (50, supplied thereto by armature 59 or a similar armature as will be described more in detail later, armature 20 and the working contact, resting contact and armature 25, through the winding of relay 11 to battery. Relay 11 operates and disconnects the talking conductors from the wipers L11 and 13 at armatures 28 and 31, respectively; prepares an energizing circuit for the switching relay 10 at armature 30; and closes the self-interrupting circuit for the stepping magnet 10 at armature 29. 1f the trunk accessible at the bank contacts a1, L15, and fio, upon which the wipers 11, 412, and 4:3 are positioned, is busy, ground potential will be present on the bank contact 15. A circuit is then completed from ground on this bank contact by way of wiper L12, armature 241- and the resting contact, armature 2f) and the working Contact interrupting contacts 39, through the winding of the stepping magnet 10 to battery. This ground potential is also extended to the lower terminal of the winding of relay 10 thereby pre enting relay 10 from energizing at this time. Stepping magnet l10 operates over the above circuit, interrupts the circuit at interrupting contacts 39, deenergizes, and in restoring, moves the switch wipers 11, L12, and 13 into engagement with the next set of bank contacts. 1f the trunk accessible at this next set of bank contact is also busy, the above operations will again take place and will be repeated until an idle trunk is found.

1t may be assumed that the trunk accessible at bank contacts 54:, 55, and 56 is idle at this time. Then the wipers 11, 112, and are moved into engagement with this set of bank contacts, no circuit is closed for the stepping magnet 40, no ground potential being present on bank contact 55. Therefore wipers 4:1, 412, and 43 are arrested in engagement with contacts 54, 55, and 5G. respectively. A circuit is now closed how ver, extending from ground by way of armature 30 and the working contact, through the winding of switching relay 10, interrupting contacts 39, through the winding of magnet L10 to battery. Magnet 4.0 does not operate over this circuit due to the high resistance of relay 10 in series therewith. Relay 10 operates however, and performs the following circuitchanges: At armatures 22 and 2T normalh7 opeu points in the talking circuit are closed. At armature 26 a point in the busy tone circuit is opened. At armature 211- in conjunction with armature 23 and the working contact, a holding circuit for switching relay 10 is established which extends from ground by way ot' the working contact and armature 19, armature 23 and the working contact, armature 24 and the working contact, through the winding of relay 10, interrupting contacts 39, through the winding of magnet ll0 to battery. At armature 25 the circuit of slow acting relay 11 is opened. By the actuation o'l= armature .13, the following additional results are affected: Ground potential is ap plied to bank contact 55 and similar contacts n'iultipled therewith by way ot' the working contact and armature 19, armature 23 and the working contact, wiper Ll2 now in engagement with Contact 55. Ground potential is at the saine time applied to bank contact 105 and the other contacts in the rotary connector banks inultipled there-with, via release conductor 105. The trunk comprising conductors 104 and 105 is thus guarded against seizure by a rotary connector or another switching mechanism having access thereto. Furthermore, the following circuits are closed: from ground on bank contact 55 through the winding of chain relay 57 to battery; and from ground on release ccnductor 105 through the winding ot cut-oliq relay 101, interrupting contacts 100, through the winding of magnet 103 to battery. Relay 57 energizes over the former circuit and closes a point in the common busy tone circuit at armature 58, and disconnects one ol the norn mal ground connections to common conductor 60. Relay 101 is energized over the latter circuit and by reason of the usual mechanical interlocking arrangement between this relay and relay 102, relay 101 operates just suinciently to disconnect the trunk conductors from their normal battery and ground connections.

A short time after its circuit is opened at armature 25, relay 11 releases its armatures and opens a point in the stepping circuit of magnet 40 at armature 29, and by releasing armatures 28 and 31 again connects the heavy talking conductors to wipers 41 and 13, respectively. A signalling circuit is new com pleted which may be traced from ground by 'way of the resting contact and armature 13, armature 27 and the working contact, resting contact and armature 31, wiper 43, bank contact 56, conductor 106, normally closed springs controlled by armature 205, condenser 214, through the winding of the AC relay 210, normally closed springs 212, normally closed springs controlled by armature 204:, trunk conductor 104;, bank Contact 5a, wiper 11, armature 26 and the resting contact, working contact and armature 22, armature 16 and the resting contact, through the upper winding of the ring cut-orf relay 8, to the common ringing conductor to which alternating current potential with battery superimposed is applied from the generator G. Alternating current from the gening call. Lamp L is lighted and remains lighted continuously until the operator answers the call. The continuous lighting of the lamp L furthermore indicates to the operator that the call is from a pay station, as distinguished from the tlashing oit the lamp Vwhen a call is extended to the operator by a subscriber at an automatic substation, as will be described in later paragraphs.

As soon as the operator at the manual eX change is ready to answer the call, she will insert the plug of an idle cord, such as the plug' P of the cord C, into the jack J at which the trunk over which the incoming call is being extended, terminates. Inserting the plug l? into the jack il separates springs 212 and closes springs 211 thereby disconnectingY the condenser 21aL and the winding of AC relay 210 trom the above traced circuit and including the lett hand windings oi' the re r peating coil l and the polarized relay 203 in the circuit, thereby closing a direct current circuit for the upper winding of relay 8. ltelay 3 operates and closes a locking circuit for its lower winding at armature 17, and at armatures 16 and 13, opens the signalling circuit and completes the talking connection to the operators position. Pelarized relay 203 is adapted to respond to current in its windv ing when liowing in a particular direction. The current in the above traced circuit now supplied through the windings ot the impedance coil 7 is in such a direction as to cause the operation of relay 203. In operating, relay 203 places a shunt around the condenser 208 at armature 20'? and the working contact, thereby closing a circuit which may be traced from this shunt through the upper and lower right hand windings of repeating coil R, tip and ring of the jack J, tip and ring oi the plug P, through the upper and lower winding of the supervisory relay 251 to battery, respectively. Relay 251 operates and opens the circuit ot the supervisory lamp L at armature 253.

After inserting the plug lD into the jack J, the operator throws the key l into the listening position thereby bridging the head set HS across the talking conductors of the cord circuit at contacts 260 and 261. The operator may now converse with the calling subscriber at substation A to learn the number of the subscriber with which connection is desired, after which she may complete the connection in any well known manner.

After the called subscriber has been summoned to his telephone, the operator requests the calling subscriber to drop the required coin in 'the slot provided for this purose in the coin box B. As the coin passes into the collecting chamber, it strikes a gong, the sound of which is transmitted to the operator by the transmitter at the calling station A, thereby informing the operator that the coin has been deposited.

After the connection has been established, the calling and called subscribers may converse as desired, and at the end of the conversation both subscribers will replace their receivers. Any Well known method Yfor giving supervision of the called line may be employed. In the cord circuit shown, supervisory relay 252 deenergizes when the alled party replaces his receiver and causes the lighting ol the lamp L2 by the engagement of armature with its resting contact the circuit of which includes the sleeve et' the plug P and the jack of the called line. In response to the replacement of the receiver at the calling substation A, the circuit ot line relay 0 is opened. Relay 0 thereupon deenergizes and opens the circuit oiF4 release relay 9 at armature 15. Release relay 9 deenergizes and releases its armatures. By the rel armature 19 the following circuit changes take place: Ground potential is removed from the private normal conductor l connected to bank contact 4 thereby again niarking the line to the substation A idle. The holding circuit for ring cut olil relay S and for the switching relay 10 are opened thereby allowing these relays to deenergize and restore their armatures lto normal. At the same time ground potential is removed from bank contact 55.

The removal ot ground from bank contact interrupts the circuit of cut-oli relay 101 in linesivitch C. In deenergizing relay 101 again connects ground and battery through line relay 102 to the trunk conductors. Since the polarized relay 203 is still bridged across the trunk conductors, the line switch C is caused to hunt an idle selector. The operation of the rotary linesivitch is well known in the art, and furthermore is similar to the operation of RLS previously described. It is thought, therefore, that a detailed description thereof need not be given. By the operation ot lineswitch C and the seizure orn an idle selector.y ground is again placed on all the appropriate bank contacts to mark the trunk comprising conductors 105; and 100 busy. I `urther1nore, current supplied to conductors 101 and 10G from line relay 102 and the line relay of the seized selector is in such a direction as to cause the deactuation of relay 203. By the release of armature 207, the circuit o1 the supervisory relay 251 is opened. In deenergizing, relay 251 closes a circuit which may be traced from ground by Way ofthe sleeve ot jack J, sleeves of plug P, armature 253 and the resting Contact, supervisory lamp L to battery. The lighting of the lamp L indicates to the operator that the subscriber at the pay station A has replaced his receiver, whereupon she will proceed to remove the plugs P and P from the ack J and the jack of the called line (not shown) respectively. Removing the plug P from the jack J opens the direct current bridge across trunk conductors 10d and 106. The seized selector and the linesiviteh C thereupon restore and remove ground potential from the appropriate contacts to again mark the said trunk idle. Removing ground from bank contact 55 also opens the circuit of the chain relay 57 which thereupon deenergizes and restores its armatures to normal. All the apparatus used in establishing the above described connection has now been restored to normal and is ready to be used to establish another call.

The operation of the ringing repeater RB, when all the interol'lice trunks accessible at the bank or' the rotary switching mechanism RLS are busy, will noiv be described. For this purpose it may be assumed that the party at the pay station A again desires to establish a connection. Responsive to the removal of the receiver at the pay station A, line relay 0 and release relay 0 again operate performing the circuit changes as described previously. lt is assumed in this case that all the trunks accessible in the bank of the rotary switch mechanism RLS are busy at this time. In this event, all the chain relays, such as relay L157, 57 and 67 shown, are energized. No ground potential is then supplied to the common conductor 60, since all the armatures which normally supply ground to this conductor via resting contacts are actuated. For this reason no circuit is closed for the line relay 11 by the actuation o'l" armature 20. Since relay 11 remains in a denergized condition, no circuit is closed for the stepping magnet Ll0. Consequently the wipers L111, l2 and 43 remain at rest. lith the armatures such as armatures 48, 58 and 68 of all the chain relays actuated, a busy tone potential is connected to the common conductor 50 from the busy machine BM. By the actuation of armature 21 the busy tone potential is connected to the loiver heavy talking conductor, and a busy tone is transmitted to the calling party at pay station A. This tone indicates to the calling party that his call is not being eX- tended 'for the time being. T he party at substation A may then replace his receiver and try to extend the connection at some other time. If he chooses, he may keep his receiver to his ear and Wait until one of the interol'lice trunks becomes idle. lVhen anyone of the interoHice trunks becomes idle, ground potential will be removed trom the release conductor of that trunk thereby causing the deenergization of' the associated chain relay. Forthepurpose of illustration, it may be assumed that the trunk comprising conductors 104 and 106 becomes idle, having previously been busy. On

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becoming idle, ground potential is removed from the conductor 105 which permits the deenergization of the chain relay 57. By the deenergization of relay 57, ground potential is again supplied to the common conductor 60 at armature 50 and the resting contact, and the busy tone circuit is disconnected at armature 58. By the application of ground on conductor 60 a circuit for the slow acting line relay 11 is again closed which operates and again performs the circuit changes as described in the previous connection. Stepping magnet 40 operates to find the idle trunk a'lfter which the connection to the operator at the manual exchange is established in the manner described above.

Since the interotlice trunks extending between the automatic exchange and the manual exchange, one of which is shown comprising the conductors 104 and 106, are accessible in the banks of rotary connectors, calls from the regular automatic subscribers to the manual exchange may also be extended thereover. Should a subscriber at a regular automatic substation such as A desire to establish a connection with a manual subscriber at the manual exchange, he first removes his receiver and dials the directory number as'- signed to the manual exchange. In response to this procedure, automatic switches will be operated, the last switch being a rotary connector which operates responsive to the last two digits dialled to select the group of trunks extending to said manual exchange, then automatically rotates to hunt an idle one oic these trunks, after which interrupted ringing current is automatically applied to the selected trunk conductors to signal the operator in a manner similar to that described in the previous connection. The operator at the manual exchange will again be notified of the incoming call by the lighting of the lamp at her position, similar to lamp L, individual to the trunk selected, and will complete the connection in the same manner as described above. In this case, interrupted generator applied to the trunk conductors causes the relay controlling the signal lamp to intermittently encrgize and deenergize, which causes the signal lamp to flash. This flashing 'further informs the operator that the call is being extended by a subscriber at a regular automatic substation, who is not required to pay in advance for cach individual call.

lWhen an interoilice trunk is seized by a rotary connector, ground potential is applied to the release conductor of that trunk, which causes the operation of the cut-oli relay of the line switch at the automaticexchange terminating that trunk, places ground potential on the test contacts individual to the seized trunk in the banks ot the rotary line switch mechanisms, such as RLS, and in the lbanks oli the vrotary connectors, to guard this trunk against seizure in other connections, The

chain relay associated with the seized trunk is also operated and performs the circuit changes previously described.

A call from a manual substation may also be -extended to any regular automatic substation such as A served by the automatic exchange. To complete such a call, the operator at the manual exchange having answered the calling manual subscriber, inserts the plug ot the cord used to answer the manual call, such as the plug P, into the jack of an idle trunk extending to the automatic eX- change. Again it may be assumed that the trunk comprising conductors 104 and 106 terminating in the jack J is the trunk used. Inserting the plug P into the jack U closes the bridge across the trunk conductors 104 and 100 by closing springs 211, this bridge including the winding ot the polarized relay 203,

Vupper and lower left hand windings of the repeating coil R, springs 211, and normally closed springs controlled by armatures 204 and 205. By reason of this bridge placed across the line conductors, a circuit is closed for the line relay 102 of the rotary line switch C, initiating the operation thereof to hunt a trunk to an idle iirst selector accessible in its bank. Then an idle trunk is found, the switching relay 101 operates to extend the connection to the selector terminating the trunk seized. As mentioned previously, current supplied to the trunk conductors from the line relay of the line switch and the line relay oiz the seized selector is in such a direction as not to cause the operation of polarized relay 203. For this reason, no circuit is closed for the supervisory relay 251 in the cord circuit OC, which therefore remains deenergizcd. The lamp L is lighted at this time over the circuit as traced previously.

After inserting the plug P into the jack J, the operator inserts the dialling plug P2 connected to the dial D into the dialling jack J individual to the jack J. Inserting the plug P2 into the jack J lirst closes the circuit of the impulsing relay 202 which may be traced from ground at the impulse springs of the dial D, tip and ring of plug P2, tip and ring of acl; J, through the winding of the relay 202 to battery. Relay 202 operates and prepares the impulsing bridge at armature 206. By the insertion of plug P2 into jack J springs 213 are closed and complete a circuit from ground at these springs through the winding of relay 201 to battery. Relay 201 operates and connects the impulsing bridge across the trunk conductors 104 and 106 at armatures 204 and 205 and their Working contacts, and disconnects the left hand windings" of the repeating coil R and the polarized relay 203, from the trunk conductors by separating the springs controlled by armatures 204 and 205.

The operator now dials the directory number uit the subscriber with which connection is desired. Actuating the dial opens the circuit of the impulsing relay 202 a number of times corresponding to the digit dialled. Each time relay 202 deenergizes, the bridge across the conductors 104 and 106 is opened at armature 206, causing the operation of automatic switches in the automatic exchange in the well known manner. When the operator has completed the dialling of the called number, she will remove the plug P2 from the jack J. Removing the plug P2 from the jack J opens the circuit of relay 201, which in releasing its armatures, disconnects the impulsing bridge from the trunk conductors and again connects the windings of the reating coil R and the polarized relay 203 in the circuit. The circuit of relay 202 is also opened which deenergizes and restores its armature to normal.

Vhen t-he called subscriber removes his receiver to answer the call, the direction of the current flow over conductors 104 and 106 is reversed in the well known manner. This reversal of current in the winding of the polarized relay 203 causes the operation of relay 208, which closes the circuit of the supervisory relay 251 at armature 207. In operating, relay 251 opens the circuit ot lamp L at armature 253, thereby indicating to the operator at the manual exchange that the called subscriber has answered.

The calling and called subscribers may now engage in conversation. The operations performed in the release of the connection are similar to those described concerning the previous connection.

Connections may also be established with the pay station line by the manual operator or by a subscriber at a regular automatic substation. In either case, to establish a connection with the paystation A automatic switches are operated responsive to digits dialled, the last switch being a regular connector, which operates to connect with the line comprising conductors 2 and 3, accessible in the connector bank contacts 2', 3 and il', or contacts multipled therewith. Vhen the connection is established, ground potential is placed on the private normal conductor 4, via bank contact 4', to mark the line busy. A circuit is then closed for the cut-off relay 5 in the ringing repeater RR. In operating, relay 5 disconnects the line conductors 2 and 3 from their normal connections to the ringinor repeater RR at armatures 13 and 14.

Vhile the ringing repeater RR has been shown in Fig. 1 as being individual to the pay Station line comprising conductors 2 and 3, it is evident that when the number of pay station lines terminating at one automatic exchange Warrants, each pay station line can be terminated directly in an individual line switch similar to the line switch C, shown in Fig. 1, in whose banks access can be given to a group of ringing repeaters, such as RR.

When this latter arrangement is used the cut-off relay, such as relay 5, may be omitted from the ringing repeater, since in the case it has no utility. The incoming conductors are then permanently connected to the upper and lower windings of line relay G.

This completes the description ot' the teature of this invention and the operation ofthe apparatus used. lVliat is considered new and is desired to have protected by Letters Patent will be specifically stated in the appended claims.

What is claimed is:

l. In a telephone system, an automatic exchange, a trunk line extending 'from said automatic exchange to a second exchange, automatic switching means at said automatic exchange for extending a call over said trunk line to said second exchange, other automatic switching means at said automatic exchange for extending a call over said trunk line from said second exchange, a paystation line, a repeater terminating said line, and automatic switching means 'or connecting said repeater to said trunk line.

2. In a telephone system, a first and a second exchange, lines terminating at each exchange, two-way trunk lines extending between said exehanges, numerical switches at said first exchange for extending connections between the lines ot the first exchange and the lines of the second exchange, another line, a repeater terminating said other line, and non-numerical switching means for connecting said repeater with an idle one of said trunk lines responsive to the initiation of a call over said other line.

In a telephone system, a first and a second exchange, two-way trunk lines extendinor between said exchanges, a calling line, repeater terminating said line, non-numerical switching means for connecting said line via said repeater with an idle one ot said trunk lines responsive to the initiation ot a call by a calling subscriber, and means for incapacitating said switching means when all said trunks are busy.

4. In a telephone system, a first and a second exchange, two-way trunk lines extending between said exchanges, a calling line, a repeater terminating said line, non-numerical switching means for connecting said line with an idle one of said trunk lines responsive to the initiation of a call by a calling subscriber, a signal, and means in said repeater for automatically operating said signal to notify an operator at said second exchange of said connection.

5. In a telephone system, a first and a second exchange, two-way trunk lines extending between said exchanges, a calling line, a repeater terminating said line, nonnumerical switching means for connecting said line with an idle one of said trunk lines responsive to the initiation of a call by a calling subscriber, means for incapacitating said switching means when all said trunks are busy, and means in said repeater' tor automatically notifying said calling subscriber ot said busy condition.

6. In a telephone system, an automatic exchange, switches at said automatic exchange for establishing connections between subscribers of said automatic exchange without the aid of an operator, a manual cxchange, trunks interconnecting said exchanges and accessible to said switches, a manual paystation in the vicinity of said automatic exchange, a line from said paystation terminating at said automatic exchange, and switching means at said automatic exchange for connecting said line with an idle one ot said trunks respon-sive to the initiation of a call from said paystation.

7. In a telephone system, an automatic exchange having automatic switches 'for completing connections between the subscribers of the exchange without the aid of an operator, a manual exchange, two-way trunks interconnecting said exchanges, a manual paystation in the vicinity of said automatic exchange, a line from said paystation terminating at said automatic exchange, switching means at said automatic exchange for connecting said line with an idle one ol said trunks responsive to the initiation ot a call from said paystation, and means for automatically notifying an operator at said manual exchange of said connection.

8. In a telephone system, an automatic exchange, a manual exchange, trunks connecting said exchanges, a paystation having lines terminating at said automatic exchange, switching means responsive to digits dialed for connecting the line of an automatic substation with an idle one of said trunks, and non-numerical switching means for connecting the line of said paystation with an idle one of said trunks.

9. In a telephone system, an automatic exchange, a manual exchange, trunks connecting said exchanges, a paystation having lines terminating at said automatic exchange, switching means responsive to digits dialed for connecting the line of an automatic substation with an idle one ot said trunks, nonnumerical switching means for connecting the line ol said paystation with an idle one of said trunks, an operators position at said manual exchange at which said trunks terminate, a signal at said position, means for operating said signal when the line of an automatic substation is connected with one oit said trunks, and means for operating said signaldilierently when the line of said paystation is connected with one of said trunks.

l0. ln a telephone system, a first exchange, a. second exchange, trunks connecting said exchanges, a line, a manual substation terminating said line, means for connecting said line with an idle one of said trunks operative Vresponsive to the initiation of a call over said line, and means including relays individual to the trunks for preventing the operation of said last means until one of said trunks becomes idle in case all ot said trunks are busy when the call is initiated.

l. In a telephone system, a lirst exchange, a second exchange, trunks connecting said exchanges, a line terminating in a manual substation, means tor connecting said line with an idle one oit said trunks operative responsive to the initiation of a call over said line, means for preventing the operation of said last means until one ot said trunks becomes idle in case all ci said trunks are busy when the call is initiated, and means including relays individual to the trunks for giving the subscriber on the line a busy tone during the time after the call is initiated and before any one oi" said trunks becomes idle.

l2. ln a telephone system, a first exchange, a second exchange, trunks connecting said exchanges, relay individual to cach trunk operated whenever the trunk with which it is -lated is busy, a line, means for connectsaid line with an idle one of said trunks operative responsive to the initiation of a call over said line, and means controlled jointly by all said relays for preventing the operation ot' said last means when all of said trunks are busy.

13. ln a telephone system, a first exchange, a secon d exchange, trunks connecting said exchanges, a relay individual to each trunk operated whenever the trunk with which it is associated is busy, a line, means for connecting said line with an idle one of said trunks operative responsive to the initiation of a call over said line, and means controlled jointly by all of said relays for giving the subscriber on the line a busy tone when all of said trunks are busy.

le. In a telephone system, an automatic exchange, a manual exchange, trunk lines interconnecting said exchanges over which connections are extended to the manual exchange by means of subscriber controlled numerical switches at the automatic exchange, a paystation having a line terminating at the automatic exchange, and non-numerical switching' means for connecting the line of said pay station with an idle one ol' the interconnecting trunk lines.

l5. In a telephone system comprising an automatic exchange and a manual exchange interconnected by trunk lines over which connections are extended from subscribers at the automatic exchange to an operators position at the manual exchange by means of numerical switches at the automatic exchange, and in which a signal at the operators position is operated in a characteristic manner when a connection is extended to the operators position by a subscriber at the automatic exchange, a manual station having a line terminating at the automatic exchange, nonnumerical switching means at the automatic exchange for extending a connection from said manual station to said operators position over one of said interconnecting trunk lines, and means for operating said signal in a different characteristic manner when a connection is extended to said operators posi 10 tion from said manual exchange.

' 16. In a telephone system, an automatic exchange, a manual exchange, trunks connecting said exchanges, a manual pay station line, non-numerical switching means in said automatic exchange for connecting said line With an idle one of said trunks responsive to the initiation of a call over said line, and means in said automatic exchange for feeding talking current over separate paths to said line and to the trunk connected with.

17. In a telephone syst-em, a iirst exchange, a second exchange, trunks connecting said exchanges, a manual line, means in said first exchange responsive when the receiver is b., lifted at said line for establishing a connection between said line and an idle one of said trunks, a source of characteristic current, means in said first exchange effective when a connection is established as set forth for con- 30 necting said current source to a conductor of the trunk connected with, and means in said firstexchange controlled over said trunk for disconnecting said current source and for completing a talking connection between said 25 line and said trunk.

18. In a telephone system, an automatic exchange, numerical switching means in said exchange, a manual line, non-numerical switching means in said exchange terminata ing said line, and a trunk accessible to both of said switching means.

In Witness whereof, I hereunto subscribe my name this 5th day of April, A. D. 1926.

CLARENCE E. LOMAX. 

